Persistence of seminal constituents in vaginal drainage samples
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Sex-related crimes are commonly encountered by forensic serologists and deoxyribonucleic acid (DNA) analysts who are tasked with detecting, screening, and analyzing seminal evidence. Traditional semen screening involves acid phosphatase (AP) testing, a microscopic examination for spermatozoa (sperm), prostate specific antigen (PSA) testing, and semenogelin (Sg) testing. Understanding the persistence of these seminal components is valuable to forensic analysts for a multitude of reasons. Although results can be variable, there is a massive amount of literature and a general understanding of the persistence of seminal acid phosphatase (SAP), sperm, PSA, and Sg when collected via post-coital vaginal swabs. However, despite the potential advantages, no formal study has been performed to determine the persistence of these seminal components in vaginal drainage samples. The objective of this study was to gain a better understanding of the persistence of AP, sperm, PSA, and Sg in post-coital vaginal drainage samples by collecting donor packets from individuals who engaged in intercourse with full ejaculation into the vagina and wore a series of panty liners to collect post-coital vaginal drainage for 120 hours (5 days). Once collected, the panty liners underwent traditional semen screening in order to determine the maximum persistence of these seminal components. In this study, the maximum persistence of a purple color change during AP testing ranged from 10 hours to 39.1 hours for post-coital vaginal drainage samples. The maximum persistence values of intact sperm ranged from 5.8 hours to 6.7 hours, while the maximum persistence values of sperm heads ranged from 0 hours to 119.6 hours. The maximum persistence values of PSA ranged from 4.5 hours to 47 hours, while the maximum persistence values for Sg ranged from 0 hours to 42.5 hours.